Automatic speed adjusting device for multiple drive conveyer system



Aug. 30, 1938. 2,128,795

AUTOMATIC SPEED ADJUSTING DEVICE FOR MULTIPLE DRIVE CONVEYER SYSTEM J.BISHOP Filed NOV. 28, 1932 2 Sheets-Sheet l 4 64 E m n 5 a I. Jr 1 w M 6J 6 a a Z M I ,0 9 I H 6 w a U 4 w F r) 3, e

Z 6 M a J k .am mm m vm Eyd m W7. W0 ZM w W/W AUTOMATIC SPEED ADJUSTINGDEVICE FOR MULTIPLE DRIVE CONVEYER SYSTEM Filed Nov. 28, 1952 2Sheets-Sheet 2 iv INVENTOR 0,? leeward J fills/$0 BY 0 I MYM;

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elsewhere for carrying articles in the process-oi Patented Aug. 30, 1938UNITED STATES AUTOMATIC SPEED ADJUSTING DEVICE FOR MULTIPLE DRIVECONVEYER SYS- TEM Leonard J. Bishop, Detroit, Mich, assignoptoMechanical Handling Systems, Inc., a corporation of Michigan ApplicationNovember 28, 1932, Serial No. 644,591

This invention relates to devices for controlling the application ofmechanical power and particularly to article conveyingsystems oi thetype now generally being employed in large factories and manufacturefrom one work station to another within a plant and where certainoperations are performed and additions made to the product thus beingcarried.

The invention also relates to systems of this general character in whicha plurality of driving units are employed about the plant for drivingdifferent sections of a chain or other continuous conveying deviceemployed in the system for supporting the products in the aforesaidprocess of manufacture.

An object of the invention is to provide a device capable of controllingthe relative speed of two moving bodies and in response either tovariations in speed or torque between the two, as occurs for example instrip mills, dynamometers, conveying systems and the like.

Another object of the invention is to provide a differential devicecapable not only of responding to variations in speed between two movingmechanical or. other parts but is capable of so adjusting the partsassociated therewith as to compensate for, or to correct such variationin speed.

Another object of the invention is to provide a mechanism capable ofautomatic speed adjustment to maintain a predetermined pull upon adriven member or product.

Another object of the invention is to synchronize the speed relationshipbetween all of the various driving units employed in the system in orderto insure that each unit will substantially do its equal share of thework involved in operating the conveyer.

Another object of the invention is to provide a single manuallyadjustable master conveyer driving unit and one or more automaticallyadjustable auxiliary driving units which are employed in driving asingle conveyer machine or similar unit where a predetermined torque isdesired.

Another object of the invention is to provide a plurality of auxiliarydriving units for a single continuous conveyer or other system and eachof which is rigidly mounted relative to the others and the entire systemand is so constructed as to respond to any variations in the pull orspeed of the several units and to compensate for such variations bydecreasing or increasing the speed of the individual units until thedesired proportion of the entire load is carried thereby.

Another object of the invention is to provide a stationary and easilyinstalled auxiliary driving unit for multiple driving unit conveyingsystems in which the speed of the driving unit is controlled by anormally balanced arm which varies the operation of the unit in suchmanner as to cause the unit to carry its proportionate share oftheentire load.

Another object of the invention is to provide a multiple driving unitconveyer system which is more economical to construct and to install,and is more reliable and accurate in its operation than the multipleunit conveyer systems heretofore employed.

Another object of the invention is to provide a multiple driving unitconveyer system having a master driving unit for controlling theoperation thereof and which will be automatically disconnected from thesystem in the event anything occurs which might otherwise cause theoverloading and eventual breakdown of the unit.

The embodiment of the invention disclosed for purposes of illustration,comprises generally a conveyer system embracing a continuous chain whichis supported by pulleys and rails' to travel throughout a manufacturingplant from one work station to another. The chain is guided andsupported in any suitable manner as by the employment of rails, forexample, and is driven at intervals by sprocket wheels, any number ofwhich may be employed to prevent excessive loads from being transferredirom one section of the chain to another. Sprocket wheels or otherequivalent devices normally are employed at all bends in the chain.although not all such devices need be driven. The sprocket wheels inturn are driven by conveyer driving units, one of which may be equippedwith a manually operable speed adjusting device to provide a masterdriving unit, while the others, or auxiliary driving units, are providedwith automatic speed adjusting mechanism for synchronizing the operationof all of the units with the main driving unit to insure the carrying ofsubstantially equal loads by all. The auxiliary units embracing theadjusting mechanisms each comprise a load responsive arm which iscapable of movement in opposite directions either to increase or todecrease the speed of the unit as the speed of the conveyer is varied bymanual adjustment of the master driving unit or otherwise. The drivingunits preferably are provided with means responsive to an overload uponthe system for discontinuing the operation of the system to preventinjury to any of the principal units of mechanism employed.

For a better understanding of the invention, reference may now be had tothe accompanying drawings in which:

Figure 1 is a diagrammatical illustration of a factory conveyer systemembracing master and auxiliary conveyer system driving units.

Figure 2 is a fragmentary side elevational view of the conveyer systemillustrated diagrammatically by Figure 1 and particularly illustratingone of the auxiliary driving units employed therein.

Figure 3 is a plan view of the driving unit structure disclosed byFigure 2.

Figure 4 is a transverse sectional view of the driving apparatus shownbyFigures 2 and 3 as it might appear substantially in the plane of linel--4 of Figure 3 and looking in the direction of the arrows thereon.

Figure 5 is a fragmentary horizontal sectional view of the drivingmechanism as it might appear substantially in the plane of line 55 ofFigure 2 and in the direction indicated by the arrows thereon.

Figure 6 is a fragmentary view of the controlling mechanism embraced inthe driving unit illustrated by the preceding figures.

Figure 'l is a fragmentary horizontal sectional view of the controllingmechanism illustrated particularly by Figure 6 and as the structuremight appear substantially in the plane of line 1-1 thereon with certainportions of the structure broken away in order better to illustrate theparts therebeneath.

Figure 8 is a view illustrating a slightly modified form of controllingmechanism embracing the principles of the invention.

Referring particularly to the drawings, in Fig. 1 there is illustrateddiagrammatically a portion of an article conveying system Iii adapted tobe employed in factories or elsewhere where such systems are desired.The conveying system Ill embraces a long continuous chain or conveyer IIwhich winds about in any desired path throughout a factory or otherestablishment, and sections i2, i3, i4 and ii of which are driven and/orguided by sprocket wheels ii, caterpillar chains. or other similardevices. While any number of sprocket wheels such as are illustrated ati6 may be employed in driving and/or changing the direction of motion ofthe chain 1 I, only a representative number are illustrated in thepresent conveying system. These sprocket wheels or other equivalentmeans may be located along the chain in any desired relation and atintervals the sprocket wheels may be driven by suitable drivingmechanism units such as those indicated at l1 and It. The distancesbetween these units should be such that each will carry substantially anequal or other desired part of the entire load involved in moving thechain throughout the factory under normal conditions. Idling sprocketsor other similar means may be employed wherever desired to change thedirection of motion of the conveyer and it is deemed unnecessary toemploy a driving unit.

The unit II, which is employed as a master driving unit comprises a wormgear mechanism it for .driving one of the sprockets ii, a so-calledReeves speed changing device 2i and a driving motor II.

The auxiliary driving mechanism units il also embrace worm reductiongears indicated at If, load responsive unit controlling mechanisms 14,

area-nus Reeves speed changing devices 2! and driving motors 21, orother suitable variable speed driving mechanism.

Since the auxiliary driving unit embraces most of the elements of themaster driving unit, only the auxiliary driving unit has beenillustrated in detail and from which illustration the master drivingunit will be easily understood.

While the conveying system ordinarily is designed to operate with onlyone master driving unit, it may embrace any desired number of auxiliarydriving units and all of which will operate synchronately and in themanner hereafter described.

The speed changing device 16, the controlling mechanism 24 and the speedreduction gear 23 of the auxiliary units i1 all are rigidly secured bybolts or other suitable means indicated at 29 to a fabricated steel orother suitable frame such as that indicated at Ii and which in thepresent instance is formed by the employment of a pair of parallel anglebars 32 and 83 and across whicha-plurality of pairs of angle bars 34, 36and 38 are rigidly secured for supporting the aforementioned units 26,24, and 28 respectively. The bars are secured together in any suitablemanner by welding, rivets, belts or other suitable means.

The Reeves speed changing device employed in all the driving units andwhich is a well known mechanism in the conveyer art, consists of a pairof parallel side frames II and 42 across which are rotatabiy supportedin bearings 43 a parallel pair of shafts M and 46. Splined on theseshafts are cone-shaped pairs of driving members 48 and 48, the twodriving members on each side of each pair being pivotally secured tobeams ii and 52 by pins indicated at 53. The beams in turn arepivot'ally supported upon the speed changing device frame by pins 54 and56 which project through the beams substantially midway between theshafts M and I6.

At one end of the mechanism the beams ii and 52 project beyond the shaftll and there are plvotally secured, as is indicated at 51, to blocksoperatively engaging oppositely threaded portions 58 and I! of a shaft Mwhich in turn is rotatably mounted adjacent the opposite ends thereof inbearings formed in the side framm Ii and 42. On one end of this shaft isdisposed a driving gear '2 which is connected by a chain it to thedriving gear 64 of a small reversible and variable speed motor Abracket81, rigidly secured to the side frame 42, provides a suitable supportfor the motor I.

When the motor rotates the shaft ii in one direction, for example, theends of the beams 5i and i2 threadably connected to the shaft by theblocks 51 are brought closer together, whereas by reason of the pivotalmountings at 54 and 56 the opposite ends of the beams are separated to agreater extent. Under such circumstances and inasmuch as one of eachpair of the cone-shaped members 4! and I! is connected to one of thebeams SI and 52, the aforesaid movement of the beams will cause thecone-shaped members 48 to progressively approach one another, whereasthecone-shaped members 49 will separate proportionally. If the shaft iiis rotated in the opposite direction, the movement of the coneshapedmembers will be the same as before except in the opposite direction.

In order to provide means for driving one of the shafts M and ii fromthe other, there is disposed upon the pairs of conical driving membersll and 48 a driving belt 88 which is formed by securing flexibly.together-a plurality of transversely disposed and rigid blocks 69. Theblocks have inclined ends which are engaged by the conical membersvarious distances from the axes thereof, depending upon the distancesapart at which the conical members are located by the operation of themotor 69. In order to positively drive the shaft 44 there is provided onan end thereof extending beyond the side frame 4|, a gear II which isoperatively associated with a chain 12 driven by a pulley I3 rigidlysecured upon the end of a motor shaft I4. The motor 16 for driving theshaft 14, is rigidly secured to a base plate I! which is adjustablyattached to the upper extremity of the side frames 4i and 42 by boltsindicated at I9. The shaft 44, which is driven by the motor I6 throughthe aforesaid.

gears and chain, in turn drives the shaft 46 through the belt 69 and thespeed ratio between the two shafts is variable in response to theoperation of the motor 66 in accordance with the position of the conicaldrive members 49 and 49. I

The controlling mechanism 24 which is located upon the frame 3I at oneside of the speed changing mechanism 26, has projecting therefrom ashaft 9| which is connected by a shaft coupling 92 with an end of theshaft 46 projecting beyond the side member 4I of the speed changingdevice frame. This shaft is received in one of a pair of alignedopenings formed between upper and lower sections 93 and 84 respectivelyof a controlling mechanism casing 96. In this opening the shaft isjournaled in a rigidly secured pair of oppositely disposed thrustbearings 91 and 99. Inside the casing 96 the end of the shaft 9| isprovided with a pinion 99 rigidly secured thereon and which meshes witha larger gear 9I which is keyed or otherwise rigidly securedintermediate the end of a short countershaft 92. Adjacent the gear 9ithe shaft 92 also has rigidly secured thereto a gear 93 corresponding insize to the driving pinion 99 previously mentioned and which meshes witha gear 94 corresponding in size to the gear 9|. The gear 94 is rigidlysecured upon the end of a shaft 99 projecting inwardly of the casing 96through the remaining one of the aforesaid pair of openings formedtherein, and is in axial alignment with the shaft BI and the gear 99.The shaft 99, like the shaft 9I, is journaled in a pair of rollerbearings I9I and I92 which are similar in every respect to the bearings91 and 83 respectively.

For supporting the shaft 92 the casing 96 has disposed therein alaterally projecting yoke or balancing arm I93 in which the oppositeends of the shaft 92 are journaled, as indicated at I94 and I96,andwhich in turn is journaled at one end in concentric relation to theshafts M and 99 upon bearings I9! and I99 formed at the inner extremityof sleeves I99 and III respectively and in the interiors of which thepairs of bearings 91, B9 and IN and I92 are likewise respectivelysecured.

When the shaft 99 is loaded and the shaft BI is driven'positively by theoperation of the motor I9, it is apparent that the shaft 99 will tend toremain stationary and the balancing arm assembly or differentialmechanism I93 to rotate in a direction opposite the shaft 9| with thegears 9I and 93 rotating idly therewith. However, when the yoke I93 isheld against rotation the'shaft 9| will drive the shaft 99 at a reducedspeed and in the same direction of rotation. The speed reduction betweenthe two shafts will be equal to the product of the number of teeth ingears 99 and 93 divided by the product of the number of teeth in gears9| and 94.

The means employed for normally holding the yoke I93 against rotation inorder to insure the driving of the shaft 99 by the shaft 9| will be morefully described hereinafter.

Connected to the shaft 99 by a coupling H2 is a shaft II3 of the wormreduction gear unit 23, which has a driven shaft H4. A flanged drivingcollar III is rigidly secured to the lower end of the shaft II4 and thesprocket wheel is secured to the collar III by shear pins II6. While anytype of conveyer may be employed with the mechanism herein disclosed, inthe present instance there is employed a chain II consisting of singlelinks II8 connected between pairs of double links II9 by suitableinterconnecting pins. The single links IIB are centrally slotted toreceive carriers I2I, the upper extremities of which are bifurcated toprovide lugs I22 supporting pairs of oppositely disposed rollers I23.These rollers are adapted to rest upon the opposite lower flanges I24 ofI-beams I29 supported in any suitable manner and at any desiredelevation throughout the factory or other place where the mechanism isemployed. Should the load on the chain become great enough to be likelyto break some part of the mechanism by which the sprocket wheel I6 isdriven, the pins IIB will be sheared off and the sprocket wheel releasedto rotate freely, upon shaft II4.

The mechanism for normally holding the yoke I93 in position seeparticularly Figs. 4 and 6) includes a balancing mechanism I3I supportedby a tubular casing I32 which is secured in a vertical position at thelower end thereof in an opening formed in the upper section 93 of thecontroller casing 96 and directly above the outer extremity of the armI93. Inside this tubular support is a long rod I33, the lower end ofwhich is threaded into a block I34 having an elongated opening I36therein through which projects a pin I31 secured at its opposite endbetween a pair of lugs I39 formed at the outer end of the arm I93. Therod is siidably mounted adjacent its lower extremity in an annularcollar I4I secured rigidly adjacent the lower extremity of the tubularmember I32 while an intermediate portion of the rod is likewise slidablydisposed in an annular collar I42 secured rigidly by studs I43 in anintermediate portion of the tubular member I32. Above the collar I42 andresting at its lower extremity thereon, is a coil spring I46, the upperextremity of which engages a washer I41 held in place upon the rod I33by a nut I49.

It will be apparent that the spring I49 will resiliently oppose thedownward movement of the free end of the arm I93.

Above the nut I49 there is secured between a spaced pair of lock nutsI6I a weight supporting plate I52 on which any desired number of weightsI63, necessary to balance the arm I93. may be placed. The bottom of theweight supporting plate I52 has secured thereto a curved leaf spring I94to the free end of which a link I69 is pivotally secured, as isindicated at I51. The opposite end of the link is secured, by a pivotalconnection indicated at I59, to the free end of an arm I69 having atransversely disposed boss portion I9I formed therein which is rotatablysecured, by a washer and cotter key indicated at I92, on the outer endof a fulcrum pin Indicated at I93. The pin I63 which projects forwardlyfrom. adjacent the upper extremity of the tubular member I32,

is threaded as is indicated at i, in an opening formed in a boss I"projecting from an annular split ring I" which is clamped around theupper extremity oi the tubular member I32. The boss Iii, from which thearm in projects, has extending laterally therefrom a pair of oppositelydisposed arms ill and I12 each arranged in position to engage one of theactuating rods i1! and I'll of a pair 0! carbon pile rheostats I16 andI" all respectively. These rheostats are vertically secured in parallelrelation upon the front of the tubular supporting member I32 by a pairof brackets Ill and I19 engaging the rheostats and the supporting memberadjacent the opposite ends of the iormer. Secured in a horizontalposition, by a bolt iii engaging the central portion of the bracket ill,is a leaf spring ill the opposite extremities of which engage the upperends of the actuating rods I13 and I'll of the rheostats I16 and ill andtend to maintain the rods in their normal upper limiting positions. Insuch positions the rods open switches located internally of therheostats I16 and I11 and which normally prevent the flow of electricalenergy therethrough.

One of the rheostats H6 is connected in an electrical circuit throughthe speed changing device actuating motor it normally causing rotationof the motor in one direction while the other rheostat I" is connectedin a circuit with the motor normally tending to rotate the motor in theopposite direction.

When, for example, the load on the chain ii increases in the vicinity ofone of the auxiliary driving units H, the arm ill! of such unit tends tomove upwardly in opposition to the weights in and in so doing actuatesthe spring iii in such manner as to rotate the boss iii upon the piniii! and to depress the arm ili against the actuating rod I'll of therheostat I16. The iirst thing to occur when this rod is depressed is theclosing of the switch of the rheostat and consequently an electricalcurrent flows through the motor Ii which tends to rotate the motor insuch direction as to separate conical members 48 and bring closertogether the conical members 48. This adjustment of the speed changingmechanism immediately decreases the rate of rotation of the shaft 46 andlikewise the shaft Bi and as a result of which the sprocket wheel itslows down and throws the excess load on the other driving units. Assoon as the load on this unit is thus decreased, the arm I" will nolonger be urged upwardly beyond its normal position but may be urgedbelow its normal position by the relative increase in the speed of thechain acting through the driven shaft 88, in which event the arm illwill depress the actuating rod of the rheostat ili thereby causing aflow of electrical energy in the opposite direction through the motor 8'and instituting its rotation in a direction opposite to that in which itpreviously was rotated by the upward movement of the arm ill. In suchevent the cone shaped members ll will be brought more closely togetherand'the members ll separated to a greater extent, thus changing thedriving ratio between the shafts M and I to cause the latter and theshaft Ii to slightly increase its speed relative to the speed of shaftI. In this manner the speed changing device driving motor I will beactuated in opposite directions until the arm I03 finally assumes itsnormal intermediate position in which the auxiliary unit underconsideration carries its proportionate share of the entire load uponthe chain.

In order to prevent the arm Ill from speeding the speed of the unitbeing decreased beyond certain limits by the upward movement of the arm"it which might be caused by an excessive load upon the conveyer. Thisstop, which is somewhat different from the stop i. comprises essentiallya bolt "2 slidably disposed in the opening in a boss ill formed in theupper half of the casing I. and the head of which normally is adjustablypositioned relative to the arm IN by a pair of lock nuts I secured uponthe bolt on the outside of the casing. The lock nuts I" normally areheld against the casing by a heavy coil spring ill surrounding the boltinside the casing and engaging the latter at the upper extremity oi thespring while the lower extremity thereof rests upon a washer ilt whichis supported by the head of the bolt. The spring illl exerts such alarge force against the head of the bolt I82 that under normalcircumstances the bolt actually will stop the upward movement of thearmilll upon the occurrence of a slightly excessive load which might aifectthe conveyer, although should the load become large enough to introducethe possibility of breaking some part oi the apparatus, the spring willbe compressed in response to the upward movement oi the bolt. Outsidethe casing there isdisposed an electrical switch I" having an arm iillengaged by the upper extremity of the bolt I92 and which arm will openan electrical circuit through the switch whenever the load is increasedto an undesirable extent and 'the end of the bolt pushes the armupwardly. The switch 1 I9! is connected in series with the driving motorI! of one of the auxiliary units or in series with the driving motors ofall oi the units which may be employed on a single conveyedandconsequently will stop the operation of the entire apparatus under theaforesaid conditions. This switch and the actuating mechanism thereformay be applied to all of the auxiliary units in addition to theemployment of the brake pins iii holding the sprocket wheels inposition, or the brake pins may be eliminated i1 desired on theauxiliary units and employed only on the sprocket wheel of the masterdriving unit.

The Reeves speed changing device employed in the master driving unit il,illustrated by Fig. 1', is practically identical to the speed changingdevices employed in the auxiliary driving units such as is illustratedin detail in Figs. 2 and 3, except for the fact that the adjustmentthereior is manually actuated by a hand wheel III secured to anadjusting shalt, such as that indicated by Ii, instead of by theemployment of an electrical motor such as that indicated at II. Thismanually adjustable speed changing unit is provided with a driven shaft2 which may be connected directly to the driving shaft 0! the wormreduction gear II or may be connected thereto by the employment of gearsI and I in combination with a chain 2".

When the article conveying system is in operation and it is desired toincrease the speed of the chain it and thus to increase the production75 area-res rate in the production line with which the conveying systemis associated, it is necessary merely to rotate the hand wheel 20! andin response to which the speed changing device 2| varies the ratiobetween the driving and driven shafts of the speed changing device andconsequently increases the speed of operation of the master driving unitsprocket wheel IS. The sprocket wheel thus tends to drive the chain IIat a greater speed than before and in which event the balancing arms I03of the more slowly driven auxiliary driving units II will tend to fallin response to the effect of the weights I53 and the increased speed ofthe driven shaft 88. Such downward movement of the weights will resultin the de: pression of the carbon pile rheostat actuating rods I14 and acircuit will be closed through the Reeves speed adjusting motors ii ofall of the auxiliary units of the system. The operation of these motorswill so adjust the speed changing devices of all of the auxiliary unitsas to increase the speed of the sprocket wheels driven thereby and, bythe reverse operation as has been heretofore described, the balancingarms I03 will assume an intermediate position when the sprocket wheelsof the auxiliary units are driven at a rate substantially equal to therate of movement of the sprocket wheel I6 of the master driving unit I8.

In order to decrease the rate of operation of the conveying system, themaster driving unit is adjusted in exactly the same manner as beforeexcept that the wheel 203 is rotated in the opposite direction.

It may be desirable in certain installations to employ a slightlymodified structure such as that illustrated by Fig. 8. This device isdesigned to permit considerable variation in load without anyappreciable variation in speed and which condition might be desirable ina conveying or other mechanism when starting up the latter at no loadother than the load imposed on the mechanism in carrying the weight ofits parts. For accomplishing this result the rod I33 is provided with a.weight ISII which is secured between the nuts ISI in place of the plateI52 embraced in the structure previously described. Several of theweights I50 of different sizes may be kept available for obtainingvariable conditions of operation in the mechanism. The weight IE6 isconsiderably smaller in diameter than the weights I53 in order to permitthe latter to rest upon a bracket I55. the lower part of which issecured adiustably upon the outer surface of the ring I61 or in anydesired position upon the tubular member I32. The upper edge of thebracket I is dapted o be so positioned that it will Partially or totallysupport the weights I53 when the balancing arm I03 is in its normalintermediate position between the stops I88 and Ill I The remainder ofthe mechanism illustrated by Fig. 8 is substantially the same as thatillustrated in the preceding figures and the same reference numerals areapplied to corresponding parts of the two structures whereverapplicable.

In the modified structure, when the mechanism is started up, thebalanclm arm III! will assume its normal intermediate position beforethe load on the mechanism is applied or when only partially applied, andwill remain in such position until the load increases to a desiredmaximum or to any other predetermined limit. During such interval theload represented by the weights I" will be progressively transferredfrom the bracket Ill to the upper surface of the weight I" and will beentirely supported by the latter when the desired maximum orpredetermined load has been applied. Any increase in the load upon themechanism beyond this limit, however, will raise the weights I" on ofthe bracket I55 and the mechanism thereafter will be slowed down throughthe operation of the arms "I and III operating the rheostats I16 andI'll respectively, as hereinbefore described.

' While the structure herein disclosed constitutes a preferred form andapplication of the invention, it is to be understood that there arenumerous other modified and equivalent structures all within the scopeof the invention defined by the appended claims.

I claim:

1. In an article conveying system, a conveying chain, a driving andspeed governing means engaging and driving said chain, said speedgoverning means having means thereon for adjusting the speed ofoperation thereof, an additional driving unit engaging and driving saidchain at 'spaced interval along the length of said chain,

said additional driving unit being connected to said chain andcomprising a source of power. a speed varying device connected therewithfor transmitting driving torque therefrom, a movable speed reductiondifferential mechanism having a torque transmitting connection with saidspeed variable device and also with said speed governing means, andmovable in response to a differential in torque between said speedvarying means and said speed governing means, and means for varying saidspeed varying device controlled by the movement of said differentialmechanism and operating continuously to vary the speed of the speedvarying device while said movable mechanism is in a position other thanits predetermined normal position.

-2. In an article conveying system, a conveyer chain, a driving andspeed governing means engaging and driving said chain, said speedgoverning means having means thereon for manually adjusting the speed ofoperation thereof, an additional driving unit engaging and driving saidchain at spaced interval along the length of said chain, said additionaldriving unit being connected to said chain and comprising a source ofpower. a speed varying device connected therewith for transmittingdriving torque therefrom, a movable speed reduction differentialmechanism, having a torque transmitting connection with said speedvariable device and also with said speed governing means through saidchain. and movable in response to a differential in torque between saidspeed varying device and said speed governing means, and means forvarying said speed varying device controlled by the movement of saiddifferential mechanism and operating continuously to vary the speed ofthe speed varying device while said movable mechanism is in a positionother than its predetermined normal position to thereby balance theloads carried by said driving units along the length of the chain.

3. The combination with a continuous conveyer, of master and auxiliarydrive units connected to different portions of said conveyer, saidmaster drive unit including means for driving said conveyer at differentpredetermined speeds, said auxiliary drive unit including variable speeddriving means and driven means, movable control means operativelyconnecting said driving and driven means and normally occupying apredetermined position, said movable means being movable in response tovariations in the torque applied by the amepas means and driven means,movable control mmns operatively connecting said driving and drivenmeans and normally Occupy a predetermined position, said movable meansbeing movable in response to variations in the torque applied by theportion of said element connected to said driven means, and means forvarying said variable speed driving means controlled by said movablemeans and operating independently oi the extent oi movement of saidcontrol means and continuing to operate while said movable means is in aposition other than its predetermined normal position.

LEONARD J. BISHOP.

CORRECTION.

CERTIFICATE OF Patent No. 2,128,795. August 50, 1938.

LEONARD J. BISHOP.

It is hereby certified that error appears in the printed specificationof the above numbered patent requiring correction as follows: Page 5,second column, line 59, claim 1, after "position" and before the period,insert the words to thereby balance the loads carried by said drivingunits along the length of the chain; and that the said Letters Patentshould be read with this correction therein that the same may conform tothe record of the case in the Patent Office.

Signed and sealed this llth day of October, A. D. 1958.

Henry Van Aredale (3 1) Acting Commissioner of Patents.

amepas means and driven means, movable control mmns operativelyconnecting said driving and driven means and normally Occupy apredetermined position, said movable means being movable in response tovariations in the torque applied by the portion of said elementconnected to said driven means, and means for varying said variablespeed driving means controlled by said movable means and operatingindependently oi the extent oi movement of said control means andcontinuing to operate while said movable means is in a position otherthan its predetermined normal position.

LEONARD J. BISHOP.

CORRECTION.

CERTIFICATE OF Patent No. 2,128,795. August 50, 1938.

LEONARD J. BISHOP.

It is hereby certified that error appears in the printed specificationof the above numbered patent requiring correction as follows: Page 5,second column, line 59, claim 1, after "position" and before the period,insert the words to thereby balance the loads carried by said drivingunits along the length of the chain; and that the said Letters Patentshould be read with this correction therein that the same may conform tothe record of the case in the Patent Office.

Signed and sealed this llth day of October, A. D. 1958.

Henry Van Aredale (3 1) Acting Commissioner of Patents.

